No power booster needed, they don’t improve braking force just the pedal effort. You can accomplish the same thing by changing the size of the master cylinder bore. A 15/16” bore master will raise the line pressure, but also make the pedal a bit lighter. You do get a little more pedal travel, but it’s not excessive and it actually allows for better pedal modulation.
DoctorDiff sells a great 15/16” aluminum master and adaptor. I run them on my Duster and my Challenger.
For more braking force, if you have A body 73-75 calipers they have a 2.6” piston. The 1976 A bodies, as well as pretty much all the other body styles, used calipers with a 2.75” piston. So you can switch to later slider calipers and get a larger piston, bolts right on, more braking force.
If you run 15” wheels you can also go to the 11.75” rotors and caliper brackets, they bolt right on to the 73+ spindles and use the same calipers. Just upsizing the rotors adds another 8% of braking fires if I remember my old calculations correctly.